This is a bit of a pet topic of mine, so I was surprised to find that I'd only written about it once before. Here I wrote on the idea that washing one's hands influences the manner in which we make moral decisions. At other times we've spoken of this topic on the podcast. Here, now, I'm going to give it a much better airing. 

I'm talking about Embodied Cognition. Generally speaking the idea behind Embodied Cognition is that our physical and physiological selves are intricately linked into the way we think and experience the world. A few examples right off the top of my head (interesting metaphor, right?) include overestimating distance and the steepness of slopes when we're encumbered vs. unencumbered, physically leaning forward when we think about the future (as well as moving our attentional spotlight to the left under the same circumstances) and self-reporting feeling happier when we're forced to smile. 

In some ways these are small things. If you want a better feel for the topic (ohh, another one) try to hold a conversation without gesturing... it'll feel amazingly unnatural and probably make the whole experience more difficult. Or maybe you could just pay attention to how people use gesture in their everyday life for a few hours. It's quite captivating once you tune into it. 

Now it may be that gesture makes sense 'cause it helps us communicate. I don't doubt this for a second, but there could easily be more to the story. Some evidence suggests gesturing seems to feedback into us and shape the way we think. 

I recently stumbled (seriously, they're everywhere) across an article which shows just that. And in a very convincing way... in my opinion.

There's a puzzle called the 'Tower of Hanoi'. Here's a picture:

The idea is that you need to move all those disks from the left to the right. There are a few rules - you may only move one piece at a time, all pieces of the puzzle must remain on the apparatus, and smaller pieces may sit on larger pieces but never larger pieces on top of smaller pieces. Once you have the hang on it, it's quite simple. 

Here's how you solve it...

Once you know the trick, it's easy. However discerning the trick is quite difficult, and most people rely on trial-and-error.

Now let me explain the paper. It was published in 2010 by Beilock and Goldin-Meadow in Psych Science. I'll start with study 2.

Participants were familiarized with the task by playing around with a three-piece variant of the Tower of Hanoi. A three piece ToH can be completed in 7 moves. Definitely not a difficult thing to do. The actual study involved a 4-piece variation, and the pieces themselves were weighted - such that the biggest piece was the heaviest and needed to be moved with two hands, and the smallest piece was the lightest. All pieces, except the heaviest, could be moved with one hand, and the weights corresponded to the size of the piece. 

Now the first phase of the experiment involved establishing a base-line - participants were timed as they solved a 4-piece variation of the task (this can be solved in 15 moves). Roughly speaking it took people about 2 minutes to figure out (I'm averaging over conditions here). They then took a break and did a time-filler task and returned to try the 4 piece puzzle again. Across both condition, on average, their speed improved by about 13 seconds. However, one group (the 'No Switch' group) used exactly the same apparatus while a second group (the 'Switch' group) used an apparatus where the smallest piece was the heaviest (and required two hands to move) and the largest piece was the lightest. In all other respects the apparatus was identical. As mentioned both groups improved their performance by about 13 seconds. 

Surprising? Not really.

Study one was identical, except that instead of doing a time-filler task between trial 1 and trial 2 participants were asked to explain how to solve the puzzle to someone naive of the task (and solution). 

You can try this right now. Try to explain to yourself how you would solve a four-piece Tower of Hanoi puzzle...

I'll give you a minute...

Did you gesture? Did you do attempt to solve the problem by moving your hands across an imaginary apparatus, moving plates through space?  I'll bet you did. Despite the fact that you probably could manage without gesture, the most efficient and intuitive way to communicate this puzzle is through gesture. Let me know in the comments if you can do this without waving your hands like a wizard.

So anyway... Study 1 was exactly the same, but they were asked to explain it to someone else between trial one and trial two (and everyone, automatically, used gestures to explain it). 

What happened? This...

People who explained the task and returned to trial two (with identical apparatus) (the 'No Switch' group) smashed it. Took about 30 seconds right off their time; more than double those in study two who weren't asked to explain the puzzle. 

The people who had the apparatus switched on them (so that the smallest piece was now the heaviest and required two hands) took longer to complete the same task. 

Is this surprising? Hell yes!

As far as the 'No Switch' group go, one might argue that gesturing/rehearsal improves their time. Particularly since those in study two didn't get to rehearse the problem during their break. However, that doesn't explain why those who had the weights switched on them in study one actually got slower - they too got to rehearse, but the rehearsal somehow interfered with their performance. 

Beilock et al argue that there's some super creepy* embodied cognition going on here. Remember that the heaviest piece required two hands to move? Beilock et al argue that the act of gesturing adds information and expectation to our understanding of the problem. Those who used the same apparatus, who rehearsed the same problem, got faster than those who didn't explain the task at all - the participants created information and expectations that was utilized in trial two. Those who had the weights switched were confronted with conflicting and incongruent information. Suddenly, those gestures that they used for the big and small piece (one- and two-handed gestures) were flipped and the information they developed became unreliable and interfered with performance. 

In fact, you find that the more people relied on one-handed gestures, the slower they got...

Pretty crazy, huh? Personally I find this fairly convincing. There's a little bit more to the paper which, if comments arise, I'll refer back to. But seriously, this is evidence that the way we use our hands influences the way our brain works.

Ponder this for a moment...

We're thinking with our fingers! 

That kind of blows my mind... and it suggests so many more questions: Does losing mobility in a limb (or just losing a limb) change the way we think about some things? How does the brain adapt to the loss of this kind of input? How does gesturing influence less concrete concepts - does big bold gesturing cement an opinion more (such as the kind used by politicians)? To what extent is it disrupting to perform a completely incongruent action while thinking in the same mode, e.g. do piano players slow down as they type if they're listening to a piano concerto? ...

Ok, sure, these are some ill-considered and highly speculative questions. To pull it back to the paper it seems that gesturing is not only reflective on the past and present (this I'm assuming is true) but predictive of the future; and it seems to have a very real influence (albeit demonstrated in this limited lab setting) over the way we think. 

I'm not sure how knowing this will influence my everyday life, but I'll certainly be paying a little more attention to my own gestures in the future. 

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*my term, not theirs....

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'Hand in a Lightbulb' photo via Shutterstock

Beilock SL, & Goldin-Meadow S (2010). Gesture changes thought by grounding it in action. Psychological science, 21 (11), 1605-10 PMID: 20889932